Taxonomy & naming
Tyrannochromis sp. "Macrostoma Short Pedicel" has no formal scientific name, describing author, or Catalog of Fishes entry. It is placed in Tyrannochromis on the strength of the genus's diagnostic build — a large, robust predatory haplochromine with an oversized jaw suited to engulfing whole fish — and on its resemblance to Tyrannochromis macrostoma, the described species after which the trade name is patterned. The qualifier "Short Pedicel" flags a body-proportion difference noted by field observers: a caudal peduncle — the muscular stalk connecting the body to the tail fin — shorter than is typical for T. macrostoma. Whether that difference marks a genuinely distinct species, a local ecotype of T. macrostoma, or simply population-level variation within it has not been resolved by a published study, and this form is treated here strictly as an undescribed trade label rather than a synonym or confirmed population of the named species.
Morphology
Tyrannochromis sp. "Macrostoma Short Pedicel" is expected to share the genus's characteristic build: a large, elongate, powerfully muscled body with a big head and an oversized, gape-limited jaw adapted for engulfing prey fish whole. Described Tyrannochromis reach substantial size — T. macrostoma is documented to about 12 in standard length, with males running larger than females — and this form is expected to fall in a broadly similar range, though no independent measurements specific to this population have been published. The feature named in the trade tag is proportional rather than a colour trait: a caudal peduncle shorter, relative to body length, than typically seen in T. macrostoma. Colour has not been documented in independently published detail for this specific population; Tyrannochromis generally show marked dichromatism, with breeding males in the genus developing brighter blue tones over a darker body while females and non-breeding fish stay a plainer silvery grey.
Habitat
This form is recorded from Kirondo, a locality on the far northern Tanzanian shore of Lake Malawi, an area that has also produced Tanzania-labelled populations of both Tyrannochromis macrostoma and the related Tyrannochromis maculiceps. Tyrannochromis as a genus are associated with sediment-free rocky and intermediate reef habitat, where they patrol as ambush predators of smaller fish rather than holding a fixed grazing territory. T. macrostoma itself is documented from a broad depth range in the lake, from shallower water near breeding females to well below 49 ft over sediment-rich rocky and intermediate zones offshore; a similarly structured predator at Kirondo is expected to use comparable habitat, though no depth data specific to this population has been published. Water conditions follow the Lake Malawi standard: warm, alkaline, and well-buffered.
Feeding
Tyrannochromis are specialist piscivores, and this form is expected to follow the same strategy documented for its genus-mates: a stealthy ambush hunter that drifts along rocky structure and lunges suddenly at smaller fish, particularly mbuna, rather than pursuing prey in open chase. The genus's oversized jaw is built for engulfing prey whole rather than tearing pieces from it. No feeding study specific to this population has been published; this account follows the well-documented genus pattern established for T. macrostoma and its relatives.
Mating
No dedicated behavioural study exists for this form. Tyrannochromis generally do not hold fixed territories the way mbuna do; described species in the genus are reported to range more widely over reef structure, with males displaying to females encountered along their patrol. As with most large predatory Malawi cichlids, there is no lasting pair bond, and courtship is expected to be brief relative to the extended parental investment that follows.
Breeding
As in all Lake Malawi haplochromines, reproduction is by maternal mouthbrooding. In T. macrostoma, the described species most similar to this form, females brood a clutch that can run into the low hundreds of eggs, incubating for roughly three weeks before releasing free-swimming fry, and continuing to shelter the young in the mouth for a period afterward even after their initial release; there is no male parental care beyond fertilisation. Clutch size and brooding details specific to this population have not been documented, and the figures above are given as genus-typical reference points rather than confirmed data for this form.
In the aquarium
Tyrannochromis sp. "Macrostoma Short Pedicel" is a rare import even by the standards of an already uncommon genus, and suits only an experienced keeper with the tank size to match a large predatory cichlid — a footprint well over 59 in is a realistic minimum given the size expected of adult Tyrannochromis. It should be housed with tankmates too large to be swallowed; small mbuna and juvenile cichlids of any species are at real risk from a fish built specifically to engulf them.
Water should replicate Lake Malawi conditions: alkaline, well-buffered, and stable, with temperature in the mid-20s Celsius and pH in the high 7s to mid 8s. Diet should be meaty and protein-rich, reflecting its predatory ecology, in contrast to the vegetable-forward diet appropriate for algae-grazing mbuna sharing the same water chemistry. Given how little independent documentation exists for this specific form, and its close resemblance to the described T. macrostoma, keepers should confirm Kirondo provenance with the dealer rather than assume any big-jawed Tyrannochromis of similar build is this population.
Conservation
Tyrannochromis sp. "Macrostoma Short Pedicel" has not been evaluated by the IUCN and, as an undescribed form, has no Red List assessment of any kind. The described species it most resembles, T. macrostoma, is assessed as Least Concern but flagged for sedimentation and ornamental-trade collection pressure within its range; large predatory cichlids across Lake Malawi generally occur at naturally low densities relative to the mbuna they prey on, which can make even modest collecting pressure meaningful for a localised population. Its known range is limited to a single locality on the Tanzanian shore, and no formal conservation status should be assumed for it pending taxonomic clarification and assessment.